Liver Dog biscuits
Use a pack of liver, pigs or ox is usually the cheapest, cover with water, bring to the boil and simmer just until firm.pour the liquid into a bowl add 1/2 tsp salt.
Chop the meat finely add to the bowl with enough wholemeal flour to make a firm dough. Roll out or make into shapes and bake in 180 oven until really hard. (You can use a food processor to make them if you have one.)